A robot wrist of the above-mentioned type is previously known from UK Patent Publication No. GB-A-2 147 877 and is characterized by a great orientation capacity. When using such a robot for alignment of laser nozzles, however, it has not been possible to utilize this orientation capacity in full, since the robot arm in certain positions conceals the beam path to the laser nozzle. The present invention provides a solution to this problem.
Robot controlled laser processing has also been proposed previously. UK Patent Publication No. GB-A-2 134 071 shows such an application. To prevent the robot arm from obstructing laser beams directed towards the nozzle, according to this publication the nozzle is supported by a special hollow arm in which a plurality of mirrors perpendicularly reflect incident beams. This arm is connected so as to be synchronously moved by the robot arm. A special wrist, which supports the laser nozzle, is fixed to the arm which is synchronously controlled by the robot arm. In addition to the inconvenience caused by an additional arm, which has no function when the robot is used for purposes other than laser processing and which increases the space requirement and the cost of the robot and complicates its manufacture, a great number of mirrors are used according to this design, both at the point of deflection of the laser beam from the source of the beam to the wrist and from the special wrist to the laser nozzle. The great number of mirrors results in a considerable loss of radiation energy when transferring the laser beam from the beam source to the nozzle.
UK Patent Publication No. GB-A-2 120 202 shows another type of robot which can be employed for laser processing. This comprises a wrist supporting a laser nozzle, the wrist being rotatably and axially displaceably supported on a vertical shaft. This shaft is supported on a horizontally displaceable car, which in turn is supported on an additional car, which is horizontally displaceable in a direction perpendicular to the direction of displacement of the first car. In addition to being able to rotate about a vertical axis, as mentioned above, the wrist can also be rotated about a horizontal axis. Also with this design, the laser beam is deflected by means of mirrors pependicularly from the laser beam source to the nozzle. This known deflection arrangement has the disadvantage that the rotary movement of the wrist is limited to about 180.degree. in order that the laser beam shall not be obstructed. A separate protective conduit of bellows type surrounds the laser beam from the source to nozzle.